Explore the vast range of titles available.

Ti-6Al-4V titanium alloy products formed by selective laser melting (SLM) are characterized by high strength and low plasticity. In addition, there may be pores inside the material, which may become a fracture sprouting point and accelerate the failure of the parts. Using an optical microscope (OM), scanning electron microscope (SEM), and electronic universal testing machine, the effects of hot isostatic pressing (HIP) parameters on the microstructure and tensile property of SLM-formed Ti-6Al-4V titanium alloy were investigated. The results show that HIP performed below the β-phase transition temperature, and the structure of the Ti-6Al-4V titanium alloy is composed of an α phase and β phase. With the increase in the HIP temperature, the α lath coarsens into a short rod, the content of the β phase increases and coarsens, and the tensile strength and yield strength of Ti-6Al-4V show a decreasing trend. With an HIP process performed at a temperature of 910 °C and pressure of 130 MPa for 2 h, the Ti-6Al-4V titanium alloy obtains the best matching of strength and plasticity.

Pre-stressed steel wire-wound ultra-high-pressure vessels (PSWUPV) are commonly used in engineering to transport ultra-high-pressure media. However, the complex structure of these containers and the frequent pressure changes pose challenges in designing their structural and fatigue strength. Three simulation design methods were compared and analyzed: the two-dimensional force method, the two-dimensional cooling method, and the three-dimensional force method. The results showed that all three methods met the stress analysis requirements. The three-dimensional surface mass force method was chosen as the preferred method for engineering applications, specifically for the process of steel wire-winding loaded with mass force. The combined load case method was used to examine the influence of steel wires on the stress of the thick-walled cylinder when wound layer-by-layer. The study also focused on the changes in stress relaxation within the steel wire layer. The results demonstrated that the residual stresses of the core cylinder and the winding layer exhibited quasi-linear superposition during the winding and preloading process. The preloading effect of the steel wire weakened with increasing friction coefficient. Simulation results showed larger errors with excessively large or small normal stiffness coefficients. Based on theoretical solutions and verification studies, the optimal friction and normal stiffness coefficients were determined to be 0.02 and 1, respectively. By achieving a reasonable distribution of residual stress in the thick-walled cylinder of the ultra-high-pressure vessel through fatigue analysis, the fatigue life of the cylinder was significantly improved.

The corrosion behavior of high-entropy alloys under cyclic wet–dry conditions simulating the salt-lake atmosphere was investigated. The composition, morphology, and electrochemical properties of the corrosion products formed on the alloy surface after corrosion were systematically analyzed. The results show that in a chloride-containing environment with alternating temperature and humidity, the Cr-containing oxide passive film formed on the alloy surface effectively inhibits the corrosion process in the early stages. In addition, electrochemical results show that the charge transfer resistance in the MgCl2 system reaches 4.96 × 105 Ω·cm2 at prolonged exposure, which is significantly higher than that in the NaCl system, indicating a lower corrosion rate. However, over time, the passive film undergoes localized rupture due to chloride ion attack and stress, leading to pitting corrosion and expansion toward the substrate. This study reveals the corrosion mechanism of high-entropy alloys in high-altitude salt-lake atmospheric environments and provides crucial insights for material design and performance optimization for their engineering applications in salt-lake scenarios.

In this study, to meet the development and application requirements for high-strength and high-toughness energetic structural materials, a representative volume element of a TA15 matrix embedded with a TaZrNb sphere was designed and fabricated via diffusion bonding. The mechanisms of the microstructural evolution of the TaZrNb/TA15 interface were investigated via SEM, EBSD, EDS, and XRD. Interface mechanical property tests and in-situ tensile tests were conducted on the sphere-containing structure, and an equivalent tensile-strength model was established for the structure. The results revealed that the TA15 titanium alloy and joint had high density and no pores or cracks. The thickness of the planar joint was approximately 50–60 μm. The average tensile and shear strengths were 767 MPa and 608 MPa, respectively. The thickness of the spherical joint was approximately 60 μm. The Zr and Nb elements in the joint diffused uniformly and formed strong bonds with Ti without forming intermetallic compounds. The interface exhibited submicron grain refinement and a concave–convex interlocking structure. The tensile fracture surface primarily exhibited intergranular fracture combined with some transgranular fracture, which constituted a quasi-brittle fracture mode. The shear fracture surface exhibited brittle fracture with regular arrangements of furrows. Internal fracture occurred along the spherical interface, as revealed by advanced in-situ X-ray microcomputed tomography. The experimental results agreed well with the theoretical predictions, indicating that the high-strength interface contributes to the overall strength and toughness of the sphere-containing structure. [Display omitted] •High-strength mechanical properties of the interface of the TA15/TaZrNb MEA composite fabricated via diffusion bonding.•Investigation on the fracture mechanisms of the RVE embedded with a sphere by in-situ μCT tensile tests.•A tensile-strength equivalent model for the RVE embedded with a sphere is established.•The concave–convex interlocking structure at the interface plays a crucial role in resisting failure.

A circular sleeve composed of CuCr1Zr alloy and 25Cr2Ni4MoV steel was effectively joined using the hot isostatic pressing (HIP) diffusion bonding technique. The interface diffusion zone of the joint underwent metallographic analysis utilizing a field-emission scanning electron microscope (FE-SEM). The findings indicated a robust bonding at the interface between the copper and steel sleeve components, devoid of any microcracks. EDS analysis reveals that the solid solution at the diffusion interface primarily consists of Cu, Cr, Fe, Ni, and C elements. Adequate diffusion transforms the mechanically interlocked interface into a metallurgical bonding interface, significantly enhancing the bonding strength and hardness of the CuCr1Zr alloy-25Cr2Ni4MoV steel bimetallic interface. Tensile testing results demonstrate that the average tensile strength of the copper matrix in the HIP diffusion-bonded assembly is 343 MPa. Fracture within the copper matrix indicates that the bonding strength at the interface exceeds this value. Additionally, the finite element method was employed to assess thermally induced stresses and strains in the CuCr1Zr alloy-25Cr2Ni4MoV steel HIP joint. The outcomes revealed that the peak equivalent residual stress within the entire joint was situated in the vicinity of the 25Cr2Ni4MoV steel, near the interface adjoining the inner wall. Simultaneously, the CuCr1Zr alloy substrate alleviated residual stress by undergoing plastic deformation.

The macroscopic mechanical properties of granular materials are closely related to their microscopic properties, and studying the compression problem of powder is helpful for establishing a constitutive law of powder compaction process. This study utilized X-ray CT technology to investigate the 3D numerical analysis model of loose particle stacking and compaction based on MPFEM, and investigated the mechanical behavior of powder under compression. The results of MPFEM were experimentally verified through powder uniaxial compression experiments, and the results showed that the calculated results of MPFEM were in good agreement with the experimental results. The method of X-ray CT can effectively capture the geometric characteristics of powder particles, and the MPFEM can obtain the true characteristics of plastic deformation of powder bodies, which is an important means of developing powder compaction constitutive models.

TA15 alloy billets were prepared by powder metallurgy-hot isostatic pressing, using 920°C, 120MPa, and a 3h holding time. Pre-alloyed powders were prepared using a plasma rotating electrode process, gas atomization, and hydrogen dehydrogenation. The particle morphology, chemical composition, particle size distribution, and microstructure of the different powders were first characterized. Then, the differences in microstructure and mechanical properties of the three alloy billets were analyzed. The results show HIP-P (tensile strength 956 MPa, elongation 16.5%) and HIP-G (tensile strength 912 MPa, elongation 16.83%) have an excellent strength-toughness combination. Although HIP-H has the highest tensile strength of 1066MPa, the elongation is only 1.3%, presenting the characteristics of high strength and low toughness. Its fracture morphology is a river pattern, a typical brittle fracture along the crystal. The ‘elemental segregation’ within the HDH powder causes the brittle fracture. This segregation leads to stress concentration during deformation, facilitating the initial propagation of cracks from the segregated regions. The high oxygen content (2200 ppm) in the HDH powder also contributes to the embrittlement observed in HIP-H. This study provides crucial insights for selecting raw powder materials and optimizing process parameters in producing HIP TA15 titanium alloy.

During the additive manufacturing of the GH4169 superalloy, various defects including cracks and holes can occur in the alloy. In this study, the effects of distinct HIP temperatures and pressure on the microstructure and mechanical properties of GH4169 were studied utilizing the metallographic microscope(OM), scanning electron microscope(SEM), X-Ray diffraction(XRD), density, microhardness, and tensile experiment. SEM and XRD results indicate that HIP can alter the texture of the matrix phase and dramatically modify the microstructure of the test alloy manufactured by SLM. Following HIP, density increases due to the pore closure of GH4169, and the hardness decreases due to the decomposition of Laves phase. Tensile testing revealed that increasing HIP temperature and pressure led to a slight reduction in the tensile strength and yield strength of the test alloy, while elongation exhibited an opposite trend. Furthermore, the increase in elongation is attributed to the improvement of the microstructure uniformity of the test alloy by HIP. And the evidence suggested that 1165°C, 155MPa is an optimal HIP parameter. Besides, the resulting alloy has a high tensile strength (1046MPa), yield strength (654MPa), and elongation (42%). The Laves phase and carbide are evenly distributed. This optimal HIP parameter will facilitate subsequent heat treatment for obtaining higher mechanical properties of the alloy.

Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized primarily by immune-mediated destruction of exocrine tissues, such as those of the salivary and lacrimal glands, resulting in the loss of saliva and tear production, respectively. This disease predominantly affects middle-aged women, often in an insidious manner with the accumulation of subtle changes in glandular function occurring over many years. Patients commonly suffer from pSS symptoms for years before receiving a diagnosis. Currently, there is no effective cure for pSS and treatment options and targeted therapy approaches are limited due to a lack of our overall understanding of the disease etiology and its underlying pathology. To better elucidate the underlying molecular nature of this disease, we have performed RNA-sequencing to generate a comprehensive global gene expression profile of minor salivary glands from an ethnically diverse cohort of patients with pSS. Gene expression analysis has identified a number of pathways and networks that are relevant in pSS pathogenesis. Moreover, our detailed integrative analysis has revealed a primary Sjögren’s syndrome molecular signature that may represent important players acting as potential drivers of this disease. Finally, we have established that the global transcriptomic changes in pSS are likely to be attributed not only to various immune cell types within the salivary gland but also epithelial cells which are likely playing a contributing role. Overall, our comprehensive studies provide a database-enriched framework and resource for the identification and examination of key pathways, mediators, and new biomarkers important in the pathogenesis of this disease with the long-term goals of facilitating earlier diagnosis of pSS and to mitigate or abrogate the progression of this debilitating disease.